John, 2024-extruded aluminum roller rockers will work just fine on the street, with the following provisos: 1- use brand name assemblies. Cheap far-east copies are of doubtful metallurgy; we call the stuff 'chinesium'. 2- Use NON-racing valve springs and 3- a 6500 rpm redline. Exceed either the spring strength or rpms very much, for very long or very often, and steel roller rockers (several good makers) are almost mandatory. Most 'steel' rockers are investment-cast-stainess, by the way.